Wired circuit board and producing method thereof

ABSTRACT

A wired circuit board, including a metal supporting layer; an insulating layer formed on one side of the metal supporting layer in a thickness direction thereof; and a conductive layer having a plurality of terminal portions placed to be spaced apart from each other and formed on one side of the insulating layer in the thickness direction. The insulating layer has a first opening which is formed to include the plurality of terminal portions, and the metal supporting layer includes a second opening formed to include the plurality of terminal portions, when projected in the thickness direction. The wired circuit board further includes at least one reinforcing insulating portion which is placed between the plurality of terminal portions in the first opening, and/or at least one reinforcing metal supporting portion which is placed between the plurality of terminal portions in the second opening, when projected in the thickness direction.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a divisional patent application of U.S.patent application Ser. No. 14/086,445 filed Nov. 21, 2013, which claimspriority from Japanese Patent Application No. 2012-257608 filed on Nov.26, 2012 and Japanese Patent Application No. 2013-163772 filed on Aug.7, 2013, the contents of which are herein incorporated by reference intothis application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wired circuit board and a producingmethod thereof, and particularly to a wired circuit board usedpreferably as a suspension board with circuit and a producing methodthereof.

2. Description of the Related Art

A wired circuit board used for electronic/electric equipment or the likeis typically formed with a terminal portion to be connected to anexternal terminal.

In recent years, to respond to the increase in the density ofelectronic/electric equipment and the reduction in the size thereof, aflying lead having a terminal portion formed not only on one surface ofa conductive pattern, but also on each of the both surfaces thereof hasbecome prevalent. For example, it has been known that, in a suspensionboard with circuit used in a hard disk drive or the like, a terminalportion is formed as a flying lead.

For example, a suspension board with circuit has been known whichincludes a supporting board, a base layer formed on the supportingboard, a conductive pattern formed as a predetermined wired circuitpattern on the base layer, and a cover layer covering the conductivepattern. In the suspension board with circuit, an opening is formed inthe cover layer to expose the top surface of the conductive pattern,while an opening is formed in the supporting board and the base layer toexpose the back surface of the conductive pattern, so that theconductive pattern the both surfaces of which are exposed is used as aflying lead (see, e.g., Japanese Unexamined Patent No. 2003-031915).

In such a suspension board with circuit, protruding portions areprovided to protrude from the insulating layers to the surfaces of theflying lead and the flying lead is provided with a wider portion toinhibit the flying lead from being disconnected due to ultrasonicvibration when the flying lead is connected to an external terminal orthe like.

SUMMARY OF THE INVENTION

In the suspension board with circuit described in Japanese UnexaminedPatent No. 2003-031915 mentioned above, when the flying lead is to beconnected to the external terminal, it is possible to inhibit the flyinglead from being disconnected. However, since the flying leadindependently exists in an opening, when an external force acts on theflying lead before and after the production of the suspension board withcircuit, the problem of warpage or breakage of the flying lead occurs.

It is therefore an object of the present invention to provide a wiredcircuit board and a producing method thereof which can suppress theoccurrence of warpage or breakage of each of terminal portions beforeand after the production of the wired circuit board.

A method of producing a wired circuit board of the present inventionincludes a first step of preparing a metal supporting layer, a secondstep of forming, on one side of the metal supporting layer in athickness direction thereof, an insulating layer having a first opening,and a plurality of terminal formation portions placed in the firstopening to be spaced apart from each other, a third step of forming, onone side of the insulating layer in the thickness direction, aconductive layer having a plurality of terminal portions eachcorresponding to the plurality of terminal formation portions, a fourthstep of partially removing the metal supporting layer to form a secondopening which includes the plurality of terminal formation portions whenprojected in the thickness direction, and at least one reinforcing metalsupporting portion placed between the plurality of terminal formationportions in the second opening, and a fifth step of removing theplurality of terminal formation portions exposed from the second openingto expose both side surfaces of the plurality of terminal portions inthe thickness direction.

In such a method of producing a wired circuit board, when the metalsupporting layer is partially removed, the second opening is formed andalso the at least one reinforcing metal supporting portion is placedbetween the plurality of terminal portions.

This allows the second opening of the metal supporting layer to bereinforced by the at least one reinforcing metal supporting portion.Therefore, even when impact or vibration is applied to a wired circuitboard in the production steps including and subsequent to the fifthstep, it is possible to protect the plurality of terminal portions withthe reinforcing metal supporting portion placed between the plurality ofterminal portions.

As a result, it is possible to suppress warpage or breakage of theterminal portions and after the production of the wired circuit board.

It is preferable that the method of producing a wired circuit board ofthe present invention further includes, after the fifth step, the stepof removing the reinforcing metal supporting portion.

In such a method of producing a wired circuit board, it is possible toprotect the terminal portions with the reinforcing metal supportingportion. In addition, by removing the reinforcing metal supportingportion, it is also possible to locate only the terminal portions in thefirst opening and the second opening when the wired circuit board isprojected in the thickness direction.

In the method of producing a wired circuit board of the presentinvention, it is preferable that, in the second step, the insulatinglayer is formed to further have, in the first opening, a reinforcinginsulating portion which overlaps the reinforcing metal supportingportion when projected in the thickness direction.

Such a method of producing a wired circuit board allows the secondopening of the metal supporting layer to be reinforced by the at leastone reinforcing metal supporting portion and also allows the firstopening of the insulating layer to be reinforced by the reinforcinginsulating portion.

Therefore, even when impact or vibration is applied to the wired circuitboard, it is possible to reliably protect the plurality of terminalportions with the reinforcing metal supporting portion and thereinforcing insulating portion which are placed between the plurality ofterminal portions.

As a result, it is possible to more reliably suppress warpage orbreakage of the terminal portions before and after the production of thewired circuit board.

It is preferable that the method of producing a wired circuit board ofthe present invention further includes the step of removing thereinforcing insulating portion.

In such a method of producing a wired circuit board, it is possible toprotect the terminal portions with the reinforcing insulating portion.In addition, by removing the reinforcing insulating portion, it is alsopossible to locate only the terminal portions in the first opening andthe second opening when the wired circuit board is projected in thethickness direction.

In the method of producing a wired circuit board of the presentinvention, it is preferable that a length of the reinforcing insulatingportion in a direction in which the plurality of terminal portions areadjacent to each other is in a range of 10% to 100% of a distancebetween the plurality of terminal portions.

In such a method of producing a wired circuit board, it is possible toprotect the terminal portions with the reinforcing insulating portionand also reliably expose both of the one surface and the other surfaceof each of the terminal portions in the thickness direction.

Therefore, it is possible to suppress warpage or breakage of theterminal portions before and after the production of the wired circuitboard and also reliably provide connection between each of the terminalportions and an external terminal.

In the method of producing a wired circuit board of the presentinvention, it is preferable that a length of the reinforcing metalsupporting portion in a direction in which the plurality of terminalportions are adjacent to each other is in a range of 10% to 100% of adistance between the plurality of terminal portions.

In such a method of producing a wired circuit board, it is possible toprotect the terminal portions with the reinforcing metal supportingportion and also reliably expose both of the one surface and the othersurface of each of the terminal portions in the thickness direction.

Therefore, it is possible to suppress warpage or breakage of theterminal portions before and after the production of the wired circuitboard and also reliably provide connection between each of the terminalportions and the external terminal.

A wired circuit board of the present invention includes a metalsupporting layer, an insulating layer formed on one side of the metalsupporting layer in a thickness direction thereof, and a conductivelayer having a plurality of terminal portions placed to be spaced apartfrom each other and formed on one side of the insulating layer in thethickness direction, wherein the insulating layer has a first openingwhich is formed to include the plurality of terminal portions whenprojected in the thickness direction, and the metal supporting layerincludes a second opening which is formed to include the plurality ofterminal portions when projected in the thickness direction. The wiredcircuit board of the present invention further includes at least onereinforcing insulating portion which is placed between the plurality ofterminal portions in the first opening when projected in the thicknessdirection and/or at least one reinforcing metal supporting portion whichis placed between the plurality of terminal portions in the secondopening when projected in the thickness direction.

Such a wired circuit board allows the first opening of the insulatinglayer and/or the second opening of the metal supporting layer to bereinforced by the at least one reinforcing insulating portion and/or theat least one reinforcing metal supporting portion. Therefore, even whenimpact or vibration is applied to the wired circuit board, it ispossible to protect the plurality of terminal portions.

As a result, it is possible to suppress warpage or breakage of theterminal portions.

In the wired circuit board of the present invention, it is preferablethat both of the reinforcing insulating portion and the reinforcingmetal supporting portion are included, and the reinforcing insulatingportion and the reinforcing metal supporting portion overlap each otherwhen projected in the thickness direction.

In such a wired circuit board, even when impact or vibration is appliedto the wired circuit board, the reinforcing insulating portion and thereinforcing metal supporting portion overlap each other to be able tohave high rigidity and allow the terminal portions to be more reliablyprotected.

Therefore, it is possible to more reliably suppress warpage or breakageof the terminal portions than in the case where only either one of thereinforcing insulating portion and the reinforcing metal supportingportion is formed.

In the wired circuit board of the present invention, it is preferablethat a length of the reinforcing insulating portion in a direction inwhich the plurality of terminal portions are adjacent to each other isin a range of 10% to 100% of a distance between the plurality ofterminal portions.

In such a wired circuit board, it is possible to protect the terminalportions with the reinforcing insulating portion and also reliablyexpose both of the one surface and the other surface of each of theterminal portions in the thickness direction.

Therefore, it is possible to suppress warpage or breakage of theterminal portions and also reliably provide connection between each ofthe terminal portions and an external terminal.

In the wired circuit board of the present invention, it is preferablethat a length of the reinforcing metal supporting portion in a directionin which the plurality of terminal portions are adjacent to each otheris in a range of 10% to 100% of a distance between the plurality ofterminal portions.

In such a wired circuit board, it is possible to protect the terminalportions with the reinforcing metal supporting portion and also reliablyexpose both of the one surface and the other surface of each of theterminal portions in the thickness direction.

Therefore, it is possible to suppress warpage or breakage of theterminal portions and also reliably provide connection between each ofthe terminal portions and the external terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a suspension board with circuit obtained inaccordance with an embodiment of a producing method of a wired circuitboard of the present invention;

FIGS. 2( a) and 2(b) are a plan view of the external connecting portionof the suspension board with circuit shown in FIG. 1,

FIG. 2( a) showing a form in which a reinforcing supporting portion isnot removed, and

FIG. 2( b) showing a form in which the reinforcing supporting portion isremoved;

FIGS. 3( a)-3(d) are a process view illustrating a method of producingthe suspension board with circuit shown in FIG. 1, which is across-sectional view along the line A-A of FIGS. 2( a) and 2(b),

FIG. 3( a) showing the step of preparing a supporting board,

FIG. 3( b) showing the step of forming an insulating base layer,

FIG. 3( c) showing the step of forming a conductive thin film, and

FIG. 3( d) showing the step of forming a plating resist;

FIGS. 4( e)-4(h) are a process view illustrating the method of producingthe suspension board with circuit shown in FIG. 1, which is subsequentto FIGS. 3( a)-3(d),

FIG. 4( e) showing the step of forming a conductive pattern,

FIG. 4( f) showing the step of removing the plating resist,

FIG. 4( g) showing the step of removing the conductive thin film exposedfrom the conductive pattern, and

FIG. 4( h) showing the step of forming an insulating cover layer;

FIGS. 5( i)-5(l) are a process view illustrating the method of producingthe suspension board with circuit shown in FIG. 1, which is subsequentto FIGS. 4( e)-4(h),

FIG. 5( i) showing the step of partially removing the supporting boardto form a supporting-board-side opening and reinforcing supportingportions,

FIG. 5( j) showing the step of removing terminal formation portionsexposed from the supporting-board-side opening,

FIG. 5( k) showing the step of plating terminal portions, and

FIG. 5( l) showing the step of removing the reinforcing supportingportions;

FIG. 6 is a plan view of the external connecting portion of thesuspension board with circuit shown in FIG. 1, which shows a form inwhich the reinforcing supporting portions and reinforcing insulatingportions are not removed;

FIGS. 7( a)-7(d) are a process view illustrating a method of producingthe suspension board with circuit shown in FIG. 1, which is across-sectional view along the line B-B of FIG. 6,

FIG. 7( a) showing the step of forming the insulating base layer havingthe reinforcing insulating portions,

FIG. 7( b) showing the step of forming the conductive thin film,

FIG. 7( c) showing the step of forming the plating resist, and

FIG. 7( d) showing the step of forming the conductive pattern;

FIGS. 8( e)-8(h) are a process view illustrating the method of producingthe suspension board with circuit shown in FIG. 1, which is subsequentto FIGS. 7( a)-7(d),

FIG. 8( e) showing the step of removing the plating resist,

FIG. 8( f) showing the step of removing the conductive thin film exposedfrom the conductive pattern,

FIG. 8( g) showing the step of forming the insulating cover layer, and

FIG. 8( h) showing the step of partially removing the supporting boardto form the supporting-board-side opening and the reinforcing supportingportions;

FIGS. 9( i)-9(l) are a process view illustrating the method of producingthe suspension board with circuit shown in FIG. 1, which is subsequentto FIGS. 8( e)-8(h),

FIG. 9( i) showing the step of removing the terminal formation portionsexposed from the supporting-board-side opening,

FIG. 9( j) showing the step of plating the terminal portions,

FIG. 9( k) showing the step of removing the reinforcing supportingportions, and

FIG. 9( l) showing the step of removing the reinforcing insulatingportions.

DETAILED DESCRIPTION OF THE INVENTION

A suspension board with circuit mounts thereon a magnetic head (notshown) in a hard disk drive to support the magnetic head, while holdinga minute gap between the magnetic head and a magnetic disk, against anair flow when the magnetic head and the magnetic disk travel relativelyto each other. The suspension board with circuit is integrally formedwith wires for connecting the magnetic head and a read/write board as anexternal circuit.

Note that, in FIG. 1, the left side corresponds to one side of asuspension board with circuit 1 in the longitudinal direction (adjacentdirection) thereof and the right side corresponds to the other side ofthe suspension board with circuit 1 in the longitudinal direction(adjacent direction) thereof. Also, in FIG. 1, the upper sidecorresponds to one side of the suspension board with circuit 1 in thewidthwise direction thereof and the lower side corresponds to the otherside of the suspension board with circuit 1 in the widthwise directionthereof. In FIGS. 3( a) to 5(l), the upper side corresponds to the upperside (one side in the thickness direction) of the suspension board withcircuit 1 and the lower side corresponds to the lower side (the otherside in the thickness direction) of the suspension board with circuit 1.

As shown in FIG. 1, the suspension board with circuit 1 is formed in agenerally rectangular flat belt shape in plan view extending in thelongitudinal direction. The suspension board with circuit 1 includes aslider mounting portion 8 which is disposed on the one longitudinal sidethereof and on which a slider (not shown) including a magnetic head (notshown) is mounted, an external connecting portion 9 which is disposed onthe other longitudinal side thereof and configured to be electricallyconnected to the read/write board (not shown) as an external board, anda wiring portion 10 extending in the longitudinal direction between theslider mounting portion 8 and the external connecting portion 9.

The suspension board with circuit 1 also includes a conductive pattern 4as an example of a conductive layer.

The conductive pattern 4 includes a plurality of (six) head-sideterminals 13, a plurality of (six) external-side terminals 14 as anexample of terminal portions, and a plurality of (six) wires 15.

The plurality of head-side terminals 13 are arranged in parallel in theslider mounting portion 8 to be widthwise spaced (preferably equallyspaced) apart from each other. The head-side terminals 13 are eachformed in a generally rectangular shape (square land) in plan view. Thehead-side terminals 13 are electrically connected to the magnetic head(not shown) of the slider (not shown).

The plurality of external-side terminals 14 are arranged in parallel inthe external connecting portion 9 to be longitudinally spaced apart fromeach other. The external-side terminals 14 are each formed in agenerally rectangular shape (square land) in plan view (see FIGS. 2( a)and 2(b)). The external-side terminals 14 are electrically connected tothe read/write board (not shown).

The plurality of wires 15 are provided so as to connect the plurality ofhead-side terminals 13 and the plurality of external-side terminals 14.Specifically, the plurality of wires 15 are arranged in parallel in thewiring portion 10 to be widthwise spaced apart from each other andformed to extend in the longitudinal direction. In the slider mountingportion 8, each of the wires 15 protrudes outwardly on both widthwisesides to extend toward the one longitudinal side. Then, the wire 15extends widthwise inwardly to be turned back toward the otherlongitudinal side so that one end portion thereof is connected to thehead-side terminal 13. In the external connecting portion 9, each of thewires 15 is bent toward the other widthwise side so that the other endportion thereof is connected to the external-side terminal 14. Note thatthe wire 15 is formed to have a width smaller than that of each of thehead-side terminals 13 and the external-side terminals 14.

As shown in FIGS. 1 and 5( l), the suspension board with circuit 1includes a supporting board 2 as an example of a metal supporting layerextending in the longitudinal direction, an insulating base layer 3 asan example of an insulating layer laminated on the upper surface of thesupporting board 2, the conductive pattern 4 laminated on the uppersurface of the insulating base layer 3, and an insulating cover layer 5(omitted in FIGS. 1, 2(a), 2(b), and 6 and shown in FIGS. 5( i)-5(l) and9(i)-9(l)) laminated on the upper surface of the insulating base layer 3so as to cover the conductive pattern 4.

In the external connecting portion 9, the supporting board 2 is formedwith a supporting-board-side opening 22 as an example of a secondopening, as shown in FIGS. 2( b) and 5(l).

The supporting-board-side opening 22 is formed in a generallyrectangular shape in plan view extending through the supporting board 2in the thickness direction to include the plurality of external-sideterminals 14 when projected in the thickness direction. Specifically,the supporting-board-side opening 22 is formed such that, in plan view,the both widthwise end edges thereof are located widthwise internally ofthe both widthwise end edges of the external-side terminals 14. Thesupporting-board-side opening 22 is also formed such that, in plan view,when the inner side and the outer side are assumed to respectivelycorrespond to the one side and the other side, the one longitudinal endedge thereof is located on the one longitudinal side of thelongitudinally innermost external-side terminal 14 and the otherlongitudinal end edge thereof is located on the other longitudinal sideof the longitudinally outermost external-side terminal 14.

In the external connecting portion 9, a base-side opening 23 as anexample of a first opening is formed in the insulating base layer 3 tocorrespond to the supporting-board-side opening 22 and a cover-sideopening 24 is formed in the insulating cover layer 5 to correspond tothe supporting-board-side opening 22. That is, when projected in thethickness direction, the base-side opening 23 and the cover-side opening24 overlap the supporting-board-side opening 22.

Thus, the plurality of external-side terminals 14 are disposed such thatthe lower surfaces thereof are exposed from the supporting-board-sideopening 22 and the base-side opening 23 and the upper surfaces thereofare exposed from the cover-side opening 24 to be configured as flyingleads. The external-side terminals 14 have a conductive thin film 18formed on each of the lower surfaces thereof and a plating layer 19formed on each of the upper surfaces and both side surfaces thereof.

Note that, as shown in FIG. 2( a), there is a form of the suspensionboard with circuit 1 in which, in the external connecting portion 9, aplurality of (five) reinforcing supporting portions 25 each as anexample of a reinforcing metal supporting portion are formed to remainwithout being removed, as is described later in detail.

The plurality of reinforcing supporting portions 25 are formed toconnect the one widthwise side of the supporting-board-side opening 22in the supporting board 2 to the other widthwise side thereof. Thereinforcing supporting portions 25 are arranged to be longitudinallyspaced (preferably equally spaced) apart from each other to be placedbetween the plurality of external-side terminals 14 when projected inthe thickness direction. In other words, the plurality of reinforcingsupporting portions 25 are disposed in the one supporting-board-sideopening 22. That is, each of the plurality of reinforcing supportingportions 25 is disposed between the external-side terminals 14 adjacentto each other when projected in the thickness direction. This means thatthe plurality of reinforcing supporting portions 25 are alternatelyarranged with the plurality of external-side terminals 14 when projectedin the thickness direction. Specifically, the reinforcing supportingportions 25 are disposed such that the longitudinal middle of each ofthe reinforcing supporting portions 25 coincides with a middle pointbetween the external-side terminals 14 adjacent to each other.

The suspension board with circuit 1 described above allows thesupporting-board-side opening 22 of the supporting board 2 to bereinforced by the plurality of reinforcing supporting portions 25.Therefore, even when impact or vibration is applied to the suspensionboard with circuit 1, the plurality of external-side terminals 14 can beprotected.

As a result, it is possible to suppress warpage or breakage of theterminal portions 14.

As shown in FIG. 6, there is also a form of the suspension board withcircuit 1 in which, in the external connecting portion 9, the pluralityof (five) reinforcing supporting portions 25 and a plurality of (five)reinforcing insulating portions 31 are formed to remain without beingremoved, as is described later in detail.

The plurality of reinforcing supporting portions 25 are placed in thesupporting-board-side opening 22 so as to alternate with the pluralityof external-side terminals 14 when projected in the thickness direction(see FIG. 2( a)).

The plurality of reinforcing insulating portions 31 are formed toconnect the one widthwise side of the base-side opening 23 to the otherwidthwise side thereof in the insulating base layer 3 and be laminatedon the upper surfaces of the corresponding reinforcing supportingportions 25. The reinforcing insulating portions 31 are arranged to belongitudinally spaced (preferably equally spaced) apart from each otherto be placed between the plurality of external-side terminals 14 whenprojected in the thickness direction. In other words, the plurality ofreinforcing insulating portions 31 are disposed in the one base-sideopening 23. That is, each of the plurality of reinforcing insulatingportions 31 is disposed between the external-side terminals 14 adjacentto each other when projected in the thickness direction. This means thatthe plurality of reinforcing insulating portions 31 are alternatelyarranged with the plurality of external-side terminals 14 when projectedin the thickness direction. Specifically, the reinforcing insulatingportions 31 are disposed such that the longitudinal middle of each ofthe reinforcing insulating portions 31 coincides with the middle pointbetween the external-side terminals 14 adjacent to each other.

In the suspension board with circuit 1 described above, the reinforcinginsulating portions 31 and the reinforcing supporting portions 25 aredisposed to overlap each other when projected in the thickness directionto be able to have high rigidity. As a result, even when impact orvibration is applied to the suspension board with circuit 1, theexternal-side terminals 14 can be protected more reliably.

Therefore, it is possible to more reliably suppress warpage or breakageof the terminal portions 14 than in the case where only either thereinforcing insulating portions 31 or the reinforcing supportingportions 25 are formed.

Next, a first method of producing the suspension board with circuit 1 inwhich the reinforcing supporting portions 25 are formed midway in theproduction process thereof is described with reference to FIGS. 3(a)-3(d), 4(e)-4(h), and 5(i)-5(l).

First, in the first producing method, as shown in FIG. 3( a), thesupporting board 2 in a flat belt shape extending in the longitudinaldirection is prepared (first step).

The supporting board 2 is formed of a metal material such as, e.g.,stainless steel, a 42-alloy, aluminum, a copper-beryllium alloy, orphosphor bronze. Preferably, the supporting board 2 is formed ofstainless steel.

Preferably, the supporting board 2 having a thickness in a range of,e.g., not less than 10 μm, or preferably not less than 15 μm and, e.g.,not more than 50 μm, or preferably not more than 35 μm is used.

Next, in the method, as shown in FIG. 3( b), the insulating base layer 3is formed on the portion of the upper surface of the supporting board 2in which the conductive pattern 4 is to be formed. At this time, in theexternal connecting portion 9, the insulating base layer 3 is formedinto a pattern formed with the base-side opening 23 which overlaps thesupporting-board-side opening 22 when projected in the thicknessdirection and with a plurality of terminal formation portions 27corresponding to the plurality of external-side terminals 14 (secondstep).

The plurality of terminal formation portions 27 are formed to connectthe one widthwise side of the base-side opening 23 to the otherwidthwise side thereof in the insulating base layer 3 and arranged to belongitudinally spaced apart from each other. Note that the terminalformation portions 27 are removed after the plurality of external-sideterminals 14 are formed on the upper surfaces thereof in the subsequentstep.

The insulating base layer 3 is formed of a synthetic resin such as,e.g., polyimide, polyamide imide, acryl, polyether nitrile, polyethersulfone, polyethylene terephthalate (PET), polyethylene naphthalate, orpolyvinyl chloride. Preferably, in terms of dimensional stabilityagainst heat, the insulating base layer 3 is preferably formed ofpolyimide.

To form the insulating base layer 3, e.g., a solution (varnish) of aphotosensitive synthetic resin is applied to the upper surface of thesupporting board 2 and dried to form a photosensitive base coating.

Then, the photosensitive base coating is exposed to light via aphotomask not shown. The photomask includes a light blocking portion,and a light full transmitting portion in a pattern. The light fulltransmitting portion is positioned to face the portion of the basecoating in which the insulating base layer 3 (including the plurality ofterminal formation portions 27) is to be formed, and the light blockingportion is positioned to face the portion (i.e., the portion in whichthe base opening 23 is to be formed) of the base coating in which theinsulating base layer 3 is not to be formed.

Then, the exposed base coating is developed and cured by heating.

As a result, the insulating base layer 3 is formed in the pattern formedwith the base-side openings 23 and with the plurality of terminalformation portions 27.

The thickness of the insulating base layer 3 (including the plurality ofterminal formation portions 27) thus formed is in a range of, e.g., notless than 1 μm, or preferably not less than 3 μm and, e.g., not morethan 35 μm, or preferably not more than 15 μm.

The width (longitudinal length) of each of the plurality of terminalformation portions 27 is set to be equal to or larger than the width(longitudinal length which is assumed to be a width L3 (shown in FIGS.2( a) and 2(b) and described later) of each of the external-sideterminals 14) of each of the external-side terminals 14, or preferablynot less than (L3+20) μm and, e.g., not more than (L3+200) μm, orpreferably equal to (L3+100) μm.

Next, in the method, the conductive pattern 4 is formed on the uppersurface of the insulating base layer 3 into the pattern formed with thehead-side terminals 13, the external-side terminals 14, and the wires15. At this time, in the external connecting portion 9, the plurality ofexternal-side terminals 14 are individually formed on the respectiveupper surfaces of the plurality of terminal formation portions 27 of theinsulating base layer 3.

To form the conductive pattern 4, the conductive pattern 4 is formed onthe upper surface of the insulating base layer 3 by a known patterningmethod such as, e.g., a subtractive method or an additive method.Preferably, the additive method is used.

In the additive method, as shown in FIG. 3( c), the conductive thin film18 is formed over the upper surface of the insulating base layer 3 andthe upper surface of the supporting board 2 exposed from the base-sideopening 23. Specifically, the conductive thin film 18 is formedcontinuously over the upper surface of the insulating base layer 3, theinner side surface of the base-side opening 23 of the insulating baselayer 3, the upper surface of the supporting board 2 exposed from thebase-side opening 23 of the insulating base layer 3, and the sidesurfaces and upper surfaces of the plurality of terminal formationportions 27 of the insulating base layer 3.

The conductive thin film 18 is formed of, e.g., chromium, copper, or thelike.

For the formation of the conductive thin film 18, a vacuum vapordeposition method, particularly sputtering is preferably used. Theconductive thin film 18 may also be a laminate of a plurality of theconductive thin films 18. Preferably, a chromium thin film is formed bysputtering. Note that the thickness of the chromium thin film is in arange of, e.g. not less than 100 Å and not more than 600 Å.

Next, as shown in FIG. 3( d), a plating resist 28 is formed on the uppersurface of the conductive thin film 18 into a pattern reverse to theconductive pattern 4 (the head-side terminals 13, the external-sideterminals 14, and the wires 15). At this time, in the externalconnecting portion 9, the plating resist 28 is formed on the uppersurface of the conductive thin film 18 into a pattern reverse to that ofthe external-side terminals 14.

The plating resist 28 is formed in the resist pattern described above bya known method using, e.g., a dry film resist or the like.

Next, as shown in FIG. 4( e), the conductive pattern 4 (the head-sideterminals 13, the external-side terminals 14, and the wires 15) isformed on the upper surface of the conductive thin film 18 exposed fromthe plating resist 28. At this time, the external-side terminals 14 areformed on the upper surface of the conductive thin film 18 (uppersurfaces of the terminal formation portions 27) exposed from the platingresist 28 (third step).

The conductive pattern 4 is formed from a conductive material such as,e.g., copper, nickel, gold, a solder, or an alloy thereof. Preferably,the conductive pattern 4 is formed of copper.

The conductive pattern 4 is formed by plating. Plating may be eitherelectrolytic plating or electroless plating, but electrolytic plating isused preferably. In particular, electrolytic copper plating is usedpreferably.

The thickness of the conductive pattern 4 thus formed is in a range of,e.g., not less than 3 μm, or preferably not less than 5 μm and, e.g.,not more than 50 μm, or preferably not more than 20 μm.

The width (widthwise length) of each of the head-side terminals 13 is ina range of, e.g., not less than 20 μm, or preferably not less than 35 μmand, e.g., not more than 100 μm, or preferably not more than 80 μm.

The spacing between the plurality of head-side terminals 13 is in arange of, e.g., not less than 20 μm, or preferably not less than 30 μmand, e.g., not more than 100 μm, or preferably not more than 80 μm.

The width of each of the external-side terminals 14 (longitudinal lengthwhich is assumed to be the width L3 (see FIGS. 2( a) and 2(b)) of theexternal-side terminal 14) is in a range of, e.g., not less than 100 μm,or preferably not less than 150 μm and, e.g., not more than 400 μm, orpreferably not more than 300 μm.

The spacing between the plurality of external-side terminals 14 (whichis assumed to be a distance L4 (see FIGS. 2( a) and 2(b)) between theexternal-side terminals 14) is in a range of, e.g., not less than 30 μm,or preferably not less than 50 μm and, e.g., not more than 800 μm, orpreferably not more than 600 μm.

The width (widthwise length) of each of the wires 15 is in a range of,e.g., not less than 8 μm, or preferably not less than 10 μm and, e.g.,not more than 250 μm, or preferably not more than 200 μm.

The spacing between the plurality of wires 15 is in a range of, e.g.,not less than 8 μm, or preferably not less than 10 μm and, e.g., notmore than 250 μm, or preferably not more than 200 μm.

Next, as shown in FIG. 4( f), the plating resist 28 is removed by, e.g.,etching, peeling, or the like.

Next, as shown in FIG. 4( g), the conductive thin film 18 exposed fromthe conductive pattern 4 (the head-side terminals 13, the external-sideterminals 14, and the wires 15) is removed by a known etching methodsuch as, e.g., wet etching (e.g., chemical etching).

As a result, the conductive pattern 4 (the head-side terminals 13, theexternal-side terminals 14, and the wires 15) is formed on the uppersurface of the conductive thin film 18.

Next, as shown in FIG. 4( h), the insulating cover layer 5 is formed onthe upper surface of the insulating base layer 3 so as to cover thewires 15 and expose the head-side terminals 13 and the external-sideterminals 14. At this time, in the external connecting portion 9, theinsulating cover layer 5 is formed in a pattern formed with thecover-side opening 24.

The insulating cover layer 5 is formed of the same synthetic resin asthat of the insulating base layer 3. Preferably, the insulating coverlayer 5 is formed of polyimide.

To form the insulating cover layer 5, e.g., a photosensitive syntheticresin (varnish) is applied to the upper surface of the insulating baselayer 3 including the wires 15 to form a photosensitive cover coating.Then, in the same manner as for the insulating base layer 3, thephotosensitive cover coating is exposed to light via a photomask notshown, developed, and cured by heating.

Thus, the insulating cover layer 5 is formed in a pattern covering thewires 15 and exposing the head-side terminals 13 and the external-sideterminals 14, e.g., in which the cover-side opening 24 is formed in theexternal connecting portion 9.

The thickness of the insulating cover layer 5 thus formed is in a rangeof, e.g., not less than 1 μm, or preferably not less than 2 μm.

Next, as shown in FIG. 5( i), in the external connecting portion 9, thesupporting board 2 is partially removed to be formed with thesupporting-board-side opening 22 and the reinforcing supporting portions25 (fourth step).

To form the supporting-board-side opening 22 and the reinforcingsupporting portions 25, for example, an etching method such as dryetching (e.g., plasma etching) or wet etching (e.g., chemical etching),drilling perforation, laser processing, or the like is used. Preferably,wet etching is used.

Thus, the supporting board 2 is processed into a pattern formed with thesupporting-board-side opening 22 and the reinforcing supporting portions25.

The supporting-board-side opening 22 thus formed has a longitudinallength which is in a range of, e.g., not less than 4000 μm, orpreferably not less than 5500 μm and, e.g., not more than 20000 μm, orpreferably not more than 10000 μm, and a widthwise length (assumed to bea width L2 (see FIGS. 2( a) and 2(b)) of the supporting-board-sideopening 22) which is in a range of, e.g., not less than 50 μm, orpreferably not less than 100 μm and, e.g., not more than 3000 μm, orpreferably not more than 2000 μm.

Each of the reinforcing supporting portions 25 thus formed has a width(longitudinal length which is assumed to be a width L1 (see FIGS. 2( a)and 2(b)) of the reinforcing supporting portion 25) which is in a rangeof, e.g., not less than 10%, or preferably not less than 30% of thedistance L4 between the external-side terminals 14 and, e.g., not morethan 100%, or preferably not more than 90% thereof. Specifically, thereinforcing supporting portion 25 is formed to have a width which is ina range of, e.g., not less than 30 μm, or preferably not less than 50 μmand, e.g., not more than 800 μm, or preferably not more than 600 μm. Thereinforcing supporting portion 25 has a length (widthwise length) whichis in a range of, e.g., not less than 50 μm, or preferably not less than100 μm and, e.g., not more than 3000 μm, or preferably not more than2000 μm.

The spacing between the plurality of reinforcing supporting portions 25is in a range of, e.g., not less than 100 μm, or preferably not lessthan 200 μm and, e.g., not more than 600 μm, or preferably not more than400 μm.

Next, as shown in FIG. 5( j), the plurality of terminal formationportions 27 of the insulating base layer 3 exposed from thesupporting-board-side opening 22 are removed by an etching method suchas wet etching (e.g., chemical etching) (fifth step).

Note that, in the wet etching, the supporting board 2 serves as anetching resist to block the wet etching of the portion of the insulatingbase layer 3 other than the terminal formation portions 27.

As a result, the plurality of external-side terminals 14 have the uppersurfaces thereof exposed from the cover-side opening 24 and the lowersurfaces thereof (i.e., the lower surface of the conductive thin film 18formed on the lower surface of each of the external-side terminals 14)exposed from the base-side opening 23 and the cover-side opening 24 tobe configured as the flying leads.

Next, as shown in FIG. 5( k), the plating layer 19 is formed over theupper surface and both side surfaces of each of the external-sideterminals 14.

The plating layer 19 is formed of, e.g., nickel, gold, or the like.

To form the plating layer 19, either an electrolytic plating method oran electroless plating method may be used. Preferably, electrolyticplating is used. The plating layer 19 may be a laminate of a pluralityof the plating layers 19. Preferably, a nickel plating layer and a goldplating layer are successively formed by electrolytic nickel plating andelectrolytic gold plating.

The thickness of the plating layer 19 thus formed (the thickness of thenickel plating layer and the gold plating layer) is in a range of, e.g.,not less than 0.05 μm, or preferably not less than 0.1 μm and, e.g., notmore than 5 μm, or preferably not more than 3 μm.

Then, as shown in FIG. 5( l), the reinforcing supporting portions 25 areremoved, while the supporting board 2 is simultaneously trimmed. Toremove the reinforcing supporting portions 25 and simultaneously trimthe supporting board 2, for example, an etching method such as dryetching (e.g., plasma etching) or wet etching (e.g., chemical etching),drilling perforation, laser processing, or the like is used. Preferably,wet etching is used.

Next, the supporting board 2 is cleaned with a cleaning solvent such as,e.g., water, methanol, or acetone and subjected to an electricalinspection and an outer appearance inspection.

In this manner, the suspension board with circuit 1 is obtained.

In such a producing method of the suspension board with circuit 1, whenthe supporting board 2 is partially removed, the supporting-board-sideopening 22 is formed, while the plurality of reinforcing supportingportions 25 are placed between the adjacent external-side terminals 14so as to alternate with the external-side terminals 14, as shown inFIGS. 5( i)-5(l).

This allows the supporting-board-side opening 22 of the supportingsubstrate 2 to be reinforced with the plurality of reinforcingsupporting portions 25. As a result, even when impact or vibration isapplied to the suspension board with circuit 1 in the subsequent steps,i.e., the step (fifth step) of removing the plurality of terminalformation portions 27 of the insulating base layer 3 exposed from thesupporting-board-side opening 22 by an etching method such as wetetching and the step of forming the plating layer 19 over the uppersurface and both side surfaces of each of the external-side terminals14, the plurality of external-side terminals 14 can be protected withthe reinforcing supporting portions 25 each placed between the pluralityof external-side terminals 14.

Consequently, in the production process of the suspension board withcircuit 1, it is possible to suppress warpage or breakage of theexternal-side terminals 14 configured as the flying leads.

Thus, in such a producing method of the suspension board with circuit 1,in the step (fifth step) of removing the plurality of terminal formationportions 27 of the insulating base layer 3 exposed from thesupporting-board-side opening 22 by an etching method such as wetetching and the step of forming the plating layer 19 over the uppersurface and side surfaces of each of the external-side terminals 14, itis possible to protect the external-side terminals 14 with thereinforcing supporting portions 25. In addition, by removing theplurality of reinforcing supporting portions 25, it is also possible tolocate only the external-side terminals 14 in the base-side opening 23and the supporting-board-side opening 22 when the suspension board withcircuit 1 is projected in the thickness direction.

Also, in the producing method of the suspension board with circuit 1 ofthe present invention, since the width L1 of each of the reinforcingsupporting portions 25 is within the range shown above relative to thedistance L4 between the external-side terminals 14, it is possible toprotect the external-side terminals 14 with the reinforcing supportingportions 25 and also reliably expose both one surface and the othersurface of each of the external-side terminals 14 in the thicknessdirection.

Therefore, in the production process of the suspension board withcircuit 1, it is possible to suppress warpage or breakage of theterminal portions 14 and also reliably provide connection between eachof the external-side terminals 14 and the external read/write board (notshown).

Next, a second method of producing the suspension board with circuit 1in which the reinforcing supporting portions 25 and the reinforcinginsulating portions 31 are formed midway in the production processthereof is described with reference to FIGS. 3( a)-3(d), 7(a)-7(d),8(e)-8(h), and 9(i)-9(l). Note that, in the producing method of thesuspension board with circuit 1 shown in FIGS. 7( a)-7(d), 8(e)-8(h),and 9(i)-9(l), a description of the same portions as those of theproducing method (hereinafter referred to as the foregoing producingmethod) of the suspension board with circuit 1 shown in FIGS. 3(a)-3(d), 4(e)-4(h), and 5(i)-5(l) is omitted.

First, in the second producing method, as shown in FIG. 3( a), thesupporting board 2 in a flat belt shape extending in the longitudinaldirection is prepared (first step).

Next, as shown in FIG. 7( a), the insulating base layer 3 is formed onthe upper surface of the supporting board 2 into a pattern formed withthe base-side opening 23 which overlaps the supporting-board-sideopening 22 when projected in the thickness direction, with the pluralityof terminal formation portions 27 corresponding to the plurality ofexternal-side terminals 14, and with the plurality of reinforcinginsulating portions 31 corresponding to the plurality of reinforcingsupporting portions 25 (second step).

More specifically, the plurality of terminal formation portions 27 areformed in the same pattern as in the foregoing producing method. Each ofthe plurality of reinforcing insulating portions 31 is formed to connectthe one widthwise side of the base-side opening 23 to the otherwidthwise side thereof in the insulating base layer 3 and placed betweenthe plurality of adjacent terminal formation portions 27. That is, theplurality of reinforcing insulating portions 31 are arranged to belongitudinally spaced apart from each other. Note that the reinforcinginsulating portions 31 are removed in the subsequent step after theplurality of reinforcing supporting portions 25 are removed.

The thickness of each of the plurality of reinforcing insulatingportions 31 thus formed is the same as that of each of the terminalformation portions 27. That is, the thickness of each of the pluralityof reinforcing insulating portions 31 is in a range of, e.g., not lessthan 1 μm, or preferably not less than 3 μm and, e.g., not more than 35μm, or preferably not more than 15 μm.

Each of the reinforcing insulating portions 31 has a width (longitudinallength which is assumed to be a width L5 (see FIG. 6) of the reinforcinginsulating portion 31) which is in a range of, e.g., not less than 10%,or preferably not less than 30% of the distance L4 between theexternal-side terminals 14 and, e.g., not more than 100%, or preferablynot more than 90% thereof. Specifically, the reinforcing insulatingportion 31 is formed to have a width which is in a range of, e.g., notless than 30 μm, or preferably not less than 50 μm and, e.g., not morethan 800 μm, or preferably not more than 600 μm. The reinforcinginsulating portion 31 has a length (widthwise length) which is in arange of, e.g., not less than 50 μm, or preferably not less than 100 μmand, e.g., not more than 3000 μm, or preferably not more than 2000 μm.

The spacing between the plurality of reinforcing insulating portions 31is in a range of, e.g., not less than 100 μm, or preferably not lessthan 200 μm and, e.g., not more than 600 μm, or preferably not more than400 μm.

Next, as shown in FIG. 7( b), the conductive thin film 18 is formed overthe upper surface of the insulating base layer 3 and the upper surfaceof the supporting board 2 exposed from the base-side opening 23.

Next, as shown in FIG. 7( c), the plating resist 28 is formed on theupper surface of the conductive thin film 18 into a pattern reverse tothe conductive pattern 4 (the head-side terminals 13, the external-sideterminals 14, and the wires 15). Note that, since the conductive pattern4 is not formed on the upper surface of each of the plurality ofreinforcing insulating portions 31, the plating resist 28 is formed soas to cover the entire reinforcing insulating portion 31.

Next, as shown in FIG. 7( d), the conductive pattern 4 (the head-sideterminals 13, the external-side terminals 14, and the wires 15) isformed on the upper surface of the conductive thin film 18 exposed fromthe plating resist 28. At this time, the external-side terminals 14 areformed on the upper surface (the upper surface of each of the terminalformation portions 27) of the conductive thin film 18 exposed from theplating resist 28 (third step).

Next, as shown in FIG. 8( e), the plating resist 28 is removed by, e.g.,etching, peeling, or the like.

Next, as shown in FIG. 8( f), the conductive thin film 18 exposed fromthe conductive pattern 4 (the head-side terminals 13, the external-sideterminals 14, and the wires 15) is removed.

Next, as shown in FIG. 8( g), the insulating cover layer 5 is formed onthe upper surface of the insulating base layer 3 so as to cover thewires 15 and expose the head-side terminals 13, the external-sideterminals 14, and the reinforcing insulating portions 31.

Next, as shown in FIG. 8( h), in the external connecting portion 9, thesupporting board 2 is partially removed to be formed with thesupporting-board-side opening 22 and the reinforcing supporting portions25 (fourth step).

Next, as shown in FIG. 9( i), the plurality of terminal formationportions 27 of the insulating base layer 3 exposed from thesupporting-board-side opening 22 are removed (fifth step).

As a result, the plurality of external-side terminals 14 have the uppersurfaces thereof exposed from the cover-side opening 24 and the lowersurfaces thereof (i.e., the lower surface of the conductive thin film 18formed on the lower surface of each of the external-side terminals 14)exposed from the base-side opening 23 and the cover-side opening 24 tobe configured as the flying leads.

Next, as shown in FIG. 9( j), the plating layer 19 is formed over theupper surface and both side surfaces of each of the external-sideterminals 14.

Next, as shown in FIG. 9( k), the reinforcing supporting portions 25 areremoved.

Then, as shown in FIG. 9( l), the plurality of reinforcing insulatingportions 31 of the insulating base layer 3 exposed from thesupporting-board-side opening 22 is removed by an etching method such aswet etching (e.g., chemical etching).

Next, the supporting board 2 is trimmed.

Next, in the same manner as in the foregoing producing method, thesupporting board 2 is cleaned with a cleaning solvent such as, e.g.,water, methanol, or acetone and subjected to an electrical inspectionand an outer appearance inspection.

In this manner, the suspension board with circuit 1 is obtained.

The configuration of the suspension board with circuit 1 thus obtainedis the same as the configuration of the suspension board with circuit 1obtained in accordance with the foregoing producing method, though theproduction processes thereof are different.

Such a producing method of the suspension board with circuit 1 allowsthe supporting-board-side opening 22 of the supporting board 2 to bereinforced by the plurality of reinforcing supporting portions 25 andalso allows the base-side opening 23 of the insulating base layer 3 tobe reinforced by the plurality of reinforcing insulating portions 31, asshown in FIGS. 9( i)-9(l).

As a result, even when impact or vibration is applied to the suspensionboard with circuit 1 in the subsequent steps, i.e., the step (fifthstep) of removing the plurality of terminal formation portions 27 of theinsulating base layer 3 exposed from the supporting-board-side opening22 by an etching method such as wet etching and the step of forming theplating layer 19 over the upper surface and both side surfaces of eachof the external-side terminals 14, the plurality of external-sideterminals 14 can be reliably protected with the reinforcing supportingportions 25 and the reinforcing insulating portions 31 each placedbetween the plurality of external-side terminals 14.

Consequently, before and after the production of the suspension boardwith circuit 1, it is possible to suppress warpage or breakage of theterminal portions 14.

Thus, in such a producing method of the suspension board with circuit 1,in the step (fifth step) of removing the plurality of terminal formationportions 27 of the insulating base layer 3 exposed from thesupporting-board-side opening 22 by an etching method such as wetetching and the step of forming the plating layer 19 over the uppersurface and side surfaces of each of the external-side terminals 14, itis possible to protect the external-side terminals 14 with thereinforcing insulating portions 31. In addition, by removing theplurality of reinforcing insulating portions 31, it is also possible tolocate only the external-side terminals 14 in the base-side opening 23and the supporting-board-side opening 22 when the suspension board withcircuit 1 is projected in the thickness direction.

Also, in such a producing method of the suspension board with circuit 1,since the width L5 of each of the reinforcing insulating portions 31 iswithin the range shown above relative to the distance L4 between theexternal-side terminals 14, it is possible to protect the external-sideterminals 14 with the reinforcing insulating portions 31 and alsoreliably expose both one surface and the other surface of each of theexternal-side terminals 14 in the thickness direction.

Therefore, in the production process of the suspension board withcircuit 1, it is possible to suppress warpage or breakage of theterminal portions 14 and also reliably provide connection between eachof the external-side terminals 14 and the external read/write board (notshown).

Referring to FIGS. 2( a) and 5(k), a modification of the first producingmethod of the wired circuit board is described. Note that, in themodification of the first producing method, the members corresponding tothe individual parts described above are designated by the samereference numerals and a detailed description thereof is omitted.

In the suspension board with circuit 1 obtained in accordance with theproducing method of the wired circuit board shown in FIGS. 3( a) to 5(l)described above, the suspension board with circuit 1 is obtained byremoving the reinforcing supporting portions 25 in the externalconnecting portion 9, as shown in FIG. 5( l). However, it is alsopossible to obtain the suspension board with circuit 1 without removingthe reinforcing supporting portions 25.

Specifically, as shown in FIG. 5( k), the plating layer 19 is formedover the upper surface and both side surfaces of each of theexternal-side terminals 14, and then the supporting board 2 is trimmedwithout removing the reinforcing supporting portions 25.

In this manner, the suspension board with circuit 1 including theexternal connecting portion 9 shown in FIGS. 2( a) and 5(k) is obtained.

In accordance with such a modification of the first producing method ofthe suspension board with circuit 1, even after the production thereof,the external-side terminals 14 can be protected with the reinforcingsupporting portions 25.

In addition, since the plurality of external-side terminals 14 areexposed from between the plurality of reinforcing supporting portions25, it is possible to reliably provide connection between each of theexternal-side terminals 14 and the external read/write board (not shown)and also suppress warpage or breakage of the terminal portions 14.

Next, referring to FIGS. 6 and 9( j), a modification of the secondproducing method of the wired circuit board is described.

Note that, in the modification of the second producing method, themembers corresponding to the individual parts described above aredesignated by the same reference numerals and a detailed descriptionthereof is omitted.

In the suspension board with circuit 1 obtained in accordance with theproducing method of the wired circuit board shown in FIGS. 7( a) to 9(l)described above, the suspension board with circuit 1 is obtained byremoving the reinforcing supporting portions 25 and the reinforcinginsulating portions 31 in the external connecting portion 9, as shown inFIGS. 9( k) and 9(l). However, it is also possible to obtain thesuspension board with circuit 1 without removing the reinforcingsupporting portions 25 and the reinforcing insulating portions 31.

Specifically, as shown in FIG. 9( j), the plating layer 19 is formedover the upper surface and both side surfaces of each of theexternal-side terminals 14, and then the supporting board 2 is trimmedwithout removing the terminal formation portions 27.

In this manner, the suspension board with circuit 1 including theexternal connecting portion 9 shown in FIGS. 6 and 9( j) is obtained.

In accordance with such a modification of the second producing method ofthe suspension board with circuit 1, even after the production thereof,the reinforcing supporting portions 25 and the reinforcing insulatingportions 31 are located so as to overlap each other. Therefore, theexternal-side terminals 14 can be more reliably protected with both ofthe reinforcing supporting portions 25 and the reinforcing insulatingportions 31.

In addition, since the plurality of external-side terminals 14 areexposed from between the plurality of reinforcing supporting portions 25and the plurality of reinforcing insulating portions 31, it is possibleto reliably provide connection between each of the external-sideterminals 14 and the external read/write board (not shown) and alsosuppress warpage or breakage of the terminal portions 14 during theconnection.

In the above-described embodiment, the plurality of terminal formationportions 27 are removed in FIG. 5 (j) and FIG. 9 (i), and thereafter theplating layer 19 is formed over the upper surface and both side surfacesof each of the plurality of external-side terminals 14 in FIG. 5 (k) andFIG. 9 (j), but for example, it is also possible to remove the pluralityof terminal formation portions 27, thereafter further remove theconductive thin film 18 formed on the lower surface of each of theplurality of external-side terminals 14 by, for example, wet etching,and then thereafter form the plating layer 19 over the upper surface,both side surfaces, and the lower surface of each of the plurality ofexternal-side terminals 14.

EXAMPLES

While in the following, the present invention will be described morespecifically with reference to EXAMPLES and COMPARATIVE EXAMPLE, thepresent invention is not limited thereto.

Example 1

A supporting board in a flat belt shape made of stainless steel, havinga thickness of 18 μm, and extending in a longitudinal direction wasprepared (see FIG. 3( a)).

Then, to the upper surface of the supporting board, a solution (varnish)of a photosensitive polyimide resin precursor was applied and dried toform a photosensitive base coating. The photosensitive base coating wasexposed to light via a photomask not shown. The photomask included alight blocking portion, and a light full transmitting portion in apattern. The light full transmitting portion was positioned to face theportion of the base coating in which an insulating base layer (includinga plurality of terminal formation portions) was to be formed, and thelight blocking portion was positioned to face the portion (i.e., theportion in which a base opening was to be formed) of the base coating inwhich the insulating base layer was not to be formed. Then, the exposedbase coating was developed and cured by heating to form the insulatingbase layer made of polyimide and having a thickness of 8 μm. At thistime, in an external connecting portion, the insulating base layer wasformed in a pattern formed with the base-side opening which overlaps asupporting-board-side opening formed later when projected in a thicknessdirection and also with a plurality of terminal formation portionscorresponding to a plurality of external-side terminals (see FIG. 3(b)).

Then, a chromium thin film having a thickness of 300 Å was formed by asputter vapor deposition method over the upper surface of the insulatingbase layer and the upper surface of the supporting board exposed fromthe base-side opening (see FIG. 3( c)).

Then, a plating resist was formed on the upper surface of the conductivethin film into a pattern reverse to a conductive pattern (head-sideterminals, the external-side terminals, and wires) (see FIG. 3( d)).

Then, by electrolytic copper plating, the conductive pattern (thehead-side terminals, the external-side terminals, and the wires) havinga thickness of 12 μm was formed on the upper surface of the conductivethin film exposed from the plating resist (see FIG. 4( e)).

The width (widthwise length) of each of the head-side terminals was 55μm.

The spacing between the plurality of head-side terminals was 32 μm.

The width of each of the external-side terminals (longitudinal lengthwhich is the width L3 of the external-side terminal) was 160 μm.

The spacing between the plurality of external-side terminals (thedistance L4 between the external-side terminals) was 420 μm.

The width (widthwise length) of each of the wires was 15 μm.

The spacing between the plurality of wires was 15 μm.

Then, the plating resist was removed by etching (see FIG. 4( f)).

Then, the conductive thin film exposed from the conductive pattern (thehead-side terminals, the external-side terminals, and the wires) wasremoved by wet etching (see FIG. 4( g)).

Then, to the upper surface of the insulating base layer including thewires, a solution (varnish) of a photosensitive polyimide resinprecursor was applied to form a photosensitive cover coating. Then, inthe same manner as for the insulating base layer, the photosensitivecover coating was exposed to light via a photomask not shown, developed,and cured by heating to form an insulating cover layer made of polyimideand having a thickness of 5 μm in a pattern covering the wires, exposingthe head-side terminals and the external-side terminals, and formed witha cover-side opening (see FIG. 4( h)).

Then, the supporting board in the external connecting portion waspartially removed by wet etching to form the supporting-board-sideopening and reinforcing supporting portions (see FIG. 4( i)).

The longitudinal length of the supporting-board-side opening was 5580μm, and the widthwise length thereof (the width L2 of thesupporting-board-side opening) was 470 μm.

The width of each of the reinforcing supporting portions (longitudinallength which is the width L1 of the reinforcing supporting portion) was300 μm, and the length (widthwise length) thereof was 470 μm.

The spacing between the plurality of reinforcing supporting portions was280 μm.

Then, the plurality of terminal formation portions of the insulatingbase layer exposed from the supporting-board-side opening were removedby wet etching to configure the external-side terminals as flying leads(see FIG. 4( j)).

Then, by electrolytic nickel plating and electrolytic gold plating, anickel plating layer having a thickness of 0.35 μm and a gold platinglayer having a thickness of 2.5 μm were successively formed over theupper surfaces and both side surfaces of the external-side terminals(see FIG. 5( k)).

Then, by wet etching, the reinforcing supporting portions were removedand the supporting board was trimmed simultaneously (see FIG. 5( l)).

In this manner, the suspension board with circuit was obtained (seeFIGS. 2( b) and 5(l)).

In the production process of the suspension board with circuit, nodeformation occurred in the external-side terminals configured as theflying leads.

Example 2

A suspension board with circuit was obtained in accordance with the samemethod as used in EXAMPLE 1 except that, in the individual stepsdescribed above, each of the reinforcing supporting portions was formedto have a width (longitudinal length which is the width L1 of thereinforcing supporting portion) of 50 μm (see FIGS. 2( b) and 5(l)).

In the production process of the suspension board with circuit, nodeformation occurred in the external-side terminals configured as theflying leads.

Example 3

A suspension board with circuit was obtained in accordance with the samemethod as used in EXAMPLE 1 except that, in the individual stepsdescribed above, the reinforcing supporting portions were not removed(see FIGS. 2( a) and 5(k)).

In the production process of the suspension board with circuit, nodeformation occurred in the external-side terminals configured as theflying leads.

Example 4

A supporting board in a flat belt shape made of stainless steel, havinga thickness of 18 μm, and extending in the longitudinal direction wasprepared (see FIG. 3( a)).

Then, to the upper surface of the supporting board, a solution (varnish)of a photosensitive polyimide resin precursor was applied and dried toform a photosensitive base coating. The photosensitive base coating wasexposed to light via a photomask not shown. The photomask included alight blocking portion, and a light full transmitting portion in apattern. The light full transmitting portion was positioned to face theportion of the base coating in which an insulating base layer (includinga plurality of terminal formation portions) was to be formed, and thelight blocking portion was positioned to face the portion (i.e., theportion in which a base opening was to be formed) of the base coating inwhich the insulating base layer was not to be formed. Then, the exposedbase coating was developed and cured by heating to form the insulatingbase layer made of polyimide and having a thickness of 8 μm. At thistime, in an external connecting portion, the insulating base layer wasformed in a pattern formed with the base-side opening which overlaps asupporting-board-side opening formed later when projected in a thicknessdirection, with a plurality of terminal formation portions correspondingto a plurality of external-side terminals, and also with a plurality ofreinforcing insulating portions (see FIG. 7( a)).

The width of each of the reinforcing insulating portions (longitudinallength which is the width L5 of the reinforcing insulating portion) was100 μm, and the length (widthwise length) thereof was 520 μm.

Then, a chromium thin film having a thickness of 300 Å was formed by asputter vapor deposition method over the upper surface of the insulatingbase layer and the upper surface of the supporting board exposed fromthe base-side opening (see FIG. 7( b)).

Then, a plating resist was formed on the upper surface of the conductivethin film into a pattern reverse to a conductive pattern (head-sideterminals, the external-side terminals, and wires) (see FIG. 7( c)).

Then, by electrolytic copper plating, the conductive pattern (thehead-side terminals, the external-side terminals, and the wires) havinga thickness of 12 μm was formed on the upper surface of the conductivethin film exposed from the plating resist (see FIG. 7( d)).

The width (widthwise length) of each of the head-side terminals was 55μm.

The spacing between the plurality of head-side terminals was 32 μm.

The width of each of the external-side terminals (longitudinal lengthwhich is the width L3 of the external-side terminal) was 200 μm.

The spacing (the distance L4 between the external-side terminals)between the plurality of external-side terminals was 520 μm.

The width (widthwise length) of each of the wires was 15 μm.

The spacing between the plurality of wires was 15 μm.

Then, the plating resist was removed by etching (see FIG. 8( e)).

Then, the conductive thin film exposed from the conductive pattern (thehead-side terminals, the external-side terminals, and the wires) wasremoved by wet etching (see FIG. 8( f)).

Then, to the upper surface of the insulating base layer including thewires, a solution (varnish) of a photosensitive polyimide resinprecursor was applied to form a photosensitive cover coating. Then, inthe same manner as for the insulating base layer, the photosensitivecover coating was exposed to light via a photomask not shown, developed,and cured by heating to form an insulating cover layer made of polyimideand having a thickness of 5 μm in a pattern covering the wires, exposingthe head-side terminals and the external-side terminals, and formed witha cover-side opening (see FIG. 8( g)).

Then, the supporting board in the external connecting portion waspartially removed by wet etching to form the supporting-board-sideopening and reinforcing supporting portions (see FIG. 8( h)).

The longitudinal length of the supporting-board-side opening was 5580μm, and the widthwise length thereof (the width L2 of thesupporting-board-side opening) was 700 μm.

The width of each of the reinforcing supporting portions (longitudinallength which is the width L1 of the reinforcing supporting portion) was60 μm, and the length (widthwise length) thereof was 700 μm.

The spacing between the plurality of reinforcing supporting portions was400 μm.

Then, the plurality of terminal formation portions of the insulatingbase layer exposed from the supporting-board-side opening were removedby wet etching to configure the external-side terminals as flying leads(see FIG. 9( i)).

Then, by electrolytic nickel plating and electrolytic gold plating, anickel plating layer having a thickness of 0.35 μm and a gold platinglayer having a thickness of 2.5 μm were successively formed over theupper surfaces and both side surfaces of the external-side terminals(see FIG. 9( j)).

Then, by wet etching, the reinforcing supporting portions were removedand the supporting board was trimmed simultaneously (see FIG. 9( k)).

Then, by wet etching, the reinforcing insulating portions were removed(see FIG. 9( l)).

In this manner, the suspension board with circuit was obtained (seeFIGS. 2( b) and 9(l)).

In the production process of the suspension board with circuit, nodeformation occurred in the external-side terminals configured as theflying leads.

Example 5

A suspension board with circuit was obtained in accordance with the samemethod as used in EXAMPLE 4 except that, in the individual stepsdescribed above, each of the reinforcing supporting portions was formedto have a width (longitudinal length which is the width L1 of thereinforcing supporting portion) of 100 μm and each of the reinforcinginsulating portions was formed to have a width (longitudinal lengthwhich is the width L5 of the reinforcing insulating portion) of 520 μm(see FIGS. 2( b) and 9(l)).

In the production process of the suspension board with circuit, nodeformation occurred in the external-side terminals configured as theflying leads.

Example 6

A suspension board with circuit was obtained in accordance with the samemethod as used in EXAMPLE 4 except that, in the individual stepsdescribed above, the reinforcing supporting portions and the reinforcinginsulating portions were not removed (see FIGS. 6 and 9( j)).

In the producing method of the suspension board with circuit, nodeformation occurred in the external-side terminals configured as theflying leads.

Comparative Example 1

A suspension board with circuit was obtained in accordance with the samemethod as used in EXAMPLE 1 except that, in the individual stepsdescribed above, when the supporting board was partially removed, onlythe supporting-board-side opening was formed and the reinforcingsupporting portions were not formed (see FIGS. 2( b) and 5(l)).

In the production process of the suspension board with circuit,deformation occurred in some of the external-side terminals configuredas the flying leads.

While the illustrative embodiments of the present invention are providedin the above description, such is for illustrative purpose only and itis not to be construed limitative. Modification and variation of thepresent invention which will be obvious to those skilled in the art isto be covered by the following claims.

What is claimed is:
 1. A wired circuit board, comprising: a metalsupporting layer; an insulating layer formed on one side of the metalsupporting layer in a thickness direction thereof; and a conductivelayer having a plurality of terminal portions placed to be spaced apartfrom each other and formed on one side of the insulating layer in thethickness direction, wherein the insulating layer has a first openingwhich is formed to include the plurality of terminal portions whenprojected in the thickness direction, and the metal supporting layerincludes a second opening which is formed to include the plurality ofterminal portions when projected in the thickness direction, the wiredcircuit board further comprising: at least one reinforcing insulatingportion which is placed between the plurality of terminal portions inthe first opening when projected in the thickness direction and/or atleast one reinforcing metal supporting portion which is placed betweenthe plurality of terminal portions in the second opening when projectedin the thickness direction.
 2. A wired circuit board according to claim1, wherein both of the reinforcing insulating portion and thereinforcing metal supporting portion are included, and the reinforcinginsulating portion and the reinforcing metal supporting portion overlapeach other when projected in the thickness direction.
 3. A wired circuitboard according to claim 1, wherein a length of the reinforcinginsulating portion in a direction in which the plurality of terminalportions are adjacent to each other is in a range of 10% to 100% of adistance between the plurality of terminal portions.
 4. A wired circuitboard according to claim 1, wherein a length of the reinforcing metalsupporting portion in a direction in which the plurality of terminalportions are adjacent to each other is in a range of 10% to 100% of adistance between the plurality of terminal portions.